Drive for a rectilinear scanner for organ imaging

ABSTRACT

Drive mechanism for a rectilinear scanner for organ imaging in which a detector and its focusing collimator is reciprocated at a constant speed across and back over the patient&#39;&#39;s organ being examined and simultaneously being gradually and continuously moved in a direction at substantially right angles to the reciprocal movement to thereby uniformly scan the entire organ.

United States Patent ONeill [54] DRIVE FOR A RECTILINEAR SCANNER FORORGAN IMAGING [72] Inventor: William J. ONeill, 459 N. Winston Dr.,Palatine, 111. 60067 [22] Filed: Nov. 30, 1970 [21] Appl. No.2 93,607

[52] US. Cl ..74/27, 128/2 A, 74/57 [51] Int. Cl ..Fl6h 21/02 [58] Fieldof Search...74/27, 57, 50, 89.15; 112/118, 112/12l.l2, 121.14; 128/2 A,2 V, 2 H, 2 R

[56] References Cited UNITED STATES PATENTS 3,001,489 9/1961 Bond et a1...112/118 3,233,450 2/1966 Fry ..l28/2.1 R 3,247,709 4/1966 Gordon..128/2 V 3,374,354 3/1968 Hood ..128/2 A 3,418,471 12/1968 Gydesen..128/2 A 3,312,184 f /1967 Cash ..1l2/l21.12

[ Aug. 15, 1972 3,442,234 5/1969 Cash ..112/1 18 2,608,697 9/ l 952Condemi ..74/27 2,840,037 6/1958 Verba ..74/27 3,334,829 8/ 1967 Fisheret a1. ..74/57 2,872,825 2/1959 Van Doren ..74/57 2,747,417 5/1956 Brown..74/57 2,552,717 5/1951 l-loughton ..74/27 Primary Examinerwilliam E.O'Dea Assistant Examiner--Wesley S. Ratliff, Jr. Attorney-Snow and Benno[57] ABSTRACT Drive mechanism for a rectilinear scanner for organimaging in which a detector and its focusing collimator is reciprocatedat a constant speed across and back over the patients organ beingexamined and simultaneously being gradually and continuously moved in adirection at substantially right angles to the reciprocal movement tothereby uniformly scan the entire organ.

5 Claims, 7 Drawing Figures Patented Aug. 15, 1972 3 Sheets-Sheet 2kflrfu e/ez' View Patented Aug. 15, 1972 3,683,706

3 Sheets-Sheet 5 DRIVE FOR A RECTILINEAR SCANNER FOR ORGAN IMAGINGBACKGROUND OF THE INVENTION 1. Field of the Invention The subjectscanner is in the field of instrumentation in nuclear medicine. Thedevice is for the purpose of detecting and locating abnormalities, suchas tumors, in various human organs. More particularly, the invention isdirected to the means for driving the detector in a predeterminedpattern over and across the organ to be tested.

2. Description of the Prior Art Scanners for detecting such organabnormalities are described in the book entitled, Instrumentation inNuclear Medicine, Edited by Gerald J. Him and Published by AcademicPress in 1967. Particular attention is directed to Chapter 16 of thisbook, entitled, Radioisotope Scanning as written by Gordon L. Brownell,Saul Aronow and Gerald J. I-Iine. Pages 381 to 387 appear pertinent to abackground knowledge of rectilinear scanners.

To obtain good readings or scans" of organs which will enable diagnosticdoctors to identify and pinpoint malignancies it is an absoluteessential that the detectors move over the organ with a uniform constantvelocity. Scanners of the past have not always been too reliable in thisregard and the result has been scans with incorrect and faulty datathereon. Also, in past scanners the path of the scanner has been ahorizontal movement of the detector, then a short vertical movement,then a return horizontal movement, and continuing in this alternatinghorizontal and vertical movement until the whole of a rectangularlyshaped outline has been scanned.

In the present invention the detector is moved with an absolute constantlinear velocity. Also, the vertical movement of the detector iscontinuous throughout the entire reciprocation of the detector so thatthe resultant movement of the detector is a zig-zag path which morecompletely and more uniformly scans an organ with reliable abnormalitydetection.

SUMMARY OF THE INVENTION A principal object of the present invention isto provide a novel drive means for a rectilinear scanner for organimaging in which the scanner is moved at a more uniform speed and at thesame time more completely scans the entire area of the organ beingexamined.

An important object of this invention is the provision of a novel drivemeans for a radioisotope scanner in which the path of travel of thescanner is zig-zag rather than a right angle jogging.

Another important object of this invention is to provide novel drivemeans for a detector in a scanning device in which the detector iscontinuously moved by a screw drive along the y coordinate of the singleplane scan area.

Still another important object of this invention is a device as setforth in the preceding object and further including a novel cam drivefor effecting reciprocation of the detector along the x coordinate ofthe single plane scan area whereupon the detector moves in a uniform,constant velocity zig-zag path.

Other and further important objects and advantages will become apparentfrom the following specification and the accompanying drawings.

In the drawings:

FIG. 1 is a perspective view of the rectilinear scanner for organimaging of this invention. a

FIG. 2 is a diagram of movement of a detector in existing scannersbefore the subject invention.

FIG. 3 is a diagram of the zig-zag movement of the detector in thescanner of this invention.

FIG. 4 is an illustration of a scan record as taken by the scanner ofthe present invention.

FIG. 5 is a sectional view of the scanner as taken on the line 5-5 ofFIG. 1.

FIG. 6 is a sectional view of the scanner as taken on the line 66 FIG.1.

FIG. 7 is a view of the detector supporting table and its drivemechanism as taken on the line 7 -7 of FIG. 6.

As shown in the drawings The reference numeral 10 indicates generally ahospital bed or table for supporting a patient during examination by theorgan imaging scanner of the present invention. The scanner 1 l isprovided with a supporting structure including a box-like housing 12containing the scanner operating mechanisms. The supporting structurefurther includes spaced apart U-shaped supports for the purpose ofcarrying the box 12 and positioning the box at a height where it will bedisposed above the bed and a patient lying on the bed. THe U- frame 13is equipped with a generally horizontal top 15 and spaced apart,generally vertically disposed legs 16 and 17. The U-frame 14 issimilarly provided with a horizontal top member 18 and spaced apart,generally vertically disposed legs 19 and 20.. Each of the legs 16, 17,19 and 20 is provided with a caster at its lower end for floorengagement. The scanner and its supporting structure is thus permittedfree rolling movement in hospitals or other areas where the device ofthis invention would be used. Also, the leg spacing is such that thedevice straddles the normal size hospital bed to eliminate the necessityfor a patient to get out of bed for movement to some table such as usedfor X-rays. The scanner also includes a control console 22 which permitsan operator to have easy access to the scanner and to his patient.

As best shown in FIG. 2 the diagram 23 depicts scan patterns as made byexisting scanners. The detector is moved in what might be termed ajogging path of horizontal and vertical movements. This jogging path ofpast scanners has a first horizontal path 24 across the top of thediagram 23 in the direction of the arrow 25. From this point thedetector moves vertically downwardly along the short path 26. This is ineffect jogging to the next scan line. Here the detector is moved backover the scan area along the second horizontal path 27 in the directionof the arrow 28. At its end of travel along the path 27 the detectorthen turns at right angles and moves downwardly along the short verticalpath 29 and thus jogs to the position of the third horizontal path 30.The detector is then moved horizontally along the path 30 in thedirection of the arrow 31. This reciprocating horizontal movement withalternate intermediate: vertical jogs is continued until all of the scanarea has been covered by the detector.

Applicants drive mechanisms eliminate the jogging of prior art scanning.As best shown in FIG. 3 the scan diagram 32 produced by applicantsdevice is a zig-zag path for the detector. There is no jogging butrather a continuous vertical movement of the detector while it ishorizontally reciprocated. The differential in speeds of the twodirections creates the desired zig-zag pattern which more thoroughlycovers the scan area and gives examining physicians an opportunity forbetter diagnosis. Horizontally the detector is moved relatively fastwhile vertically the detector moves relatively slow. However, in bothmovements the speeds are constant and uniform. This absolutely constantspeed of travel of the detector over the scan area prevents faultyinformation from being recorded on the scan diagram.

In FIG. 3 the detector of applicants scanner moves in a first angularpath 33 across the diagram 32 with primarily horizontal movement andjust slight downward or vertical movement. The arrow 34 indicates thedirection of movement of the detector along the path 33. Now thedetector is reversed and moves along a second angular path 35 in itsreturn across the scan area as shown by the arrow 36. Again the movementof the detector is primarily horizontal with only slight verticalmovement. When the detector reaches the end of the path 35 it is againreversed and now moves back across the scan area on a third angular path37 in the direction of the arrow 38. This zig-zag movement of thedetector continues until the entire area to be scanned has beentraversed. The resultant scan is one in which there is less spacebetween scan lines than in scans made by prior scanners with theresultant that diagnosticians need interpolate less with applicantsdevice.

Further in FIG. 3 there is included on the diagram vertically disposed,horizontally spaced apart lines 39 and 40 which define the lateralextent of the organ of the patient being examined on the diagram. Thusthe center portion of the scan is used for material readings by thescanner. The overtravel at each end of the reversing detector isutilized to overcome slight velocity variations in the detector at theend of each pass across the scanarea that would be caused by thereversal of movement. In each reversal the velocity must be reduced tozero and then the device accelerated to resume its constant uniformspeed of travel.

In FIG. 4 an attempt has been made to reproduce an actual scan made beapplicants device. However, rather than scanning a human organ the fieldto be scanned was provided with two separate sources of radiation. Onewas considerably larger than the other and they were spaced apart. Thephotograph made by this artificial radiation field is reproduced in partin FIG. 4 as indicated by the numeral 41. In this illustration thezig-zag lines are seen as well as the larger and more intense radiationsource shown at 43 and the lesser radiation source shown at 44. Thesesources of radiation were recorded by the detector in its zig-zag pathof travel over the scan area. The illustration also shows the relativelyuniform field produced by the detector in its movement over the scanfield. This of course means that truer readings can be made byapplicants scanner in its use on human patients with less chance oferror.

FIGS. and 6 show the interior of the housing 12 which includes all ofthe operating mechanisms of the scanner of this invention. The housing12 is provided with a top 45, a bottom 46 and spaced apart end walls 47and 48. The box housing preferably includes reinforcing frame membersand a covering skin of lightweight sheet metal. The end wall members 47and 48 are carried by the supporting legs 16, 17, 19 and 20.

Within the housing 12 there are spaced apart brackets 49 and 50 whichare fixedly attached to and depend from the top 45. As best shown inFIG. 6 a third bracket 51 is attached to and depends from the top 45 ata position in axial alignment with the bracket 49. The aligned brackets49 and 51 fixedly support a cylindrical rod 52. A spaced apart andparallel rod 53 is fixedly suspended beneath the bracket 50 and anotherbracket (not shown) in axial alignment therewith which is similar to thebracket 51.

A bracket 54 is mounted to and on the underside of the top 45 at aposition generally between the spaced brackets 49 and 50 as shown inFIG. 6. The bracket 54 carries a motor 55 for the driving of thedetector in its vertical direction in a manner to be subsequentlydescribed. The motor 55 is provided with a drive shaft 56, the axis ofwhich lies parallel to the top 45 of the housing 12. The drive shaft isprovided with a coupling 57 which joins the drive shaft with a threadedscrew shaft 58. The drive shaft 56 and the screw shaft 58 are in axialalignment. The screw shaft is journaled for rotation within the housing12 by spaced apart hanger bearings 59 and 60 depending from theunderside of the top 45. As best shown in FIG. 6 an internally threadednut-bracket 61 is shown engaging the threaded shaft 58. Bolt fasteningmeans 62 are used to join the nut-bracket 61 to a movable frame 63 whichis joumally supported on the spaced rod members 52 and 53 for movementtherealong. This is accomplished by a plurality of sleeve-like bearings64. It is preferable that these bearings 64 be ball bushings todrastically minimize friction in the movement of the frame 63 along thespaced rods 52 and 53.

A second motor 65 is provided in applicants device to provide the sourceof power for driving the detector in its reciprocal horizontal movement.The second motor 65 is carried on and moves with the frame 63. The driveshaft 66 of the motor 65 is disposed on a generally vertical axis asshown in FIG. 6. As best shown in FIG. 5 spaced apart brackets 67 and 68are affixed to the movable frame 63 and are arranged in axial alignmentto receive and carry a rod 69. Similar spaced apart brackets 70 arearranged to fixedly carry a rod 71 which is spaced from the rod 69 butparallel thereto. THe rods 69 and 71 are disposed at right angles to theguide rods 52 and 53. The frame 63 with its motor 65 moves as a unitalong the supporting guide rods 52 and 53 and itself has supportingguide rods to permit the detector to be moved in a direction at rightangles to the direction of movement of the frame 63.

A detector supporting table 72 is disposed beneath the movalbe frame 63and by means of sleeve bearings 73 the table is slidably carried on theguide rods 69 and 71. The sleeve hearings in this instance also arepreferably in the form of ball bushings in order to minimize frictionand to insure accuracy and uniformity of travel of the detector in itsscanning of an organ.

The lower end of the motor drive shaft 66 is provided with a drive arm74 which extends radially outwardly from the shaft. The attachment ofthe drive arm 74 to the shaft is such that rotation of the shaft causesrotation of the arm. This is more clearly shown in FIG. 7. A camfollower in the form of a roller 75 is journally mounted on the end ofthe drive arm spaced from its attachment to the motor drive shaft 66.The table 72 is provided with a diagonally positioned cam block 76. Theblock is bolted or otherwise fastened to the table so that it forms anintegral part therewith. The block is equipped with an elongated grooveor cam track 77 which is disposed generally diagonally of the table. Thewidth of the cam groove 77 is commensurate with the size of the camroller 75. The roller 75 engages the groove and the drive arm 74 isrotated in a single direction in its circular path 78 in the directionof the arrows 79 the table 72 is caused to have reciprocal movementalong the guide rods 69 and 71. The reciprocal linear movement of thetable 72 is indicated by the double ended arrows 80 in FIGS. 5 and 7.The cam drive thus converts rotary motion to a reciprocal linear motion.The shape of the cam 77 is designed with a long sweeping curvethroughout the major portion of its length and with relatively shortcurve endings. It is this particular cam shape that permits the cam toslide easily therethrough and drive the table 72 in a continuousreciprocating movement although the direction of rotation of the motor65 is constant in one direction.

The actual detecting portions of applicants scanner are carried on thetable 72. A radiation detector 81 is mounted on the underside of thetable 72. A multiplier photo tube 82 forms a part of the detector.Similarly the detector includes a crystal 83, such as sodium iodide, todetect radiation and impart energy impulses to a circuit (not shown)which includes an oscilloscope (also not shown). The readings of theoscilloscope may be recorded by a camera or the like (not shown).

The detector still further includes a collimator 84. The drawings show alarge rectangular opening 85 in the bottom 46 of the housing 12 topermit the small aperture or apertures 86 of the collimator to bedirected downwardly on a patient 87.

In the use of the device of this invention the patient 87 is placed onthe bed 10 and the scanner placed above him in the area of the organ tobe tested. The usual procedure is to preliminarily feed or inject someradioactive pharmaceutical to the patient. The particular radioactivepharmaceutical used would be one which the medical profession hasdiscovered will lodge in the particular organ to be tested. Not onlywill the radiation substance be attracted to a particular organ butnuclear medicine personnel have found that such radiation substanceswill accumulate in greater or lesser amounts in diseased area of theorgan. This is especially true of tumors having cellular structure quiteabnormal compared to the normal cell structure of the organ. The patientso prepared is then subjected to this scanning test and the detector ineffect takes a picture of the organ. Aggregations or lack thereof of theradioactive drugs in one or more areas of the organ indicate to themedical profession that the organ is diseased. The detector of thisinvention moves at a constant uniform speed in two directions in asingle plane in the zigzag path previously described and enables thescanner to record meaningful data.

Radiation beams 88 are received through the collimator 84 andconcentrated on the crystal 83. The scanner thus encompasses the entireorgan to be examined by the linear movements of the detector in twodirections at right angles to one another and producing a zig-zag pathby reason of the particular drive employed. The horizontal scanning isaccomplished by the cam drive in the direction of the arrow and thevertical scanning is accomplished by the screw drive in the direction ofthe arrow 89. The arrow 89 has been made two ended to show not that thedetector reciprocates vertically during one scan, but that the detectorcan be moved back to start over or may be reversed to start a scan fromthe other end. The vertical movement of the detector during a scan runscontinuously from one end of the drive screw to the other.

What is claimed is:

1. A drive mechanism for a rectilinear scanner for organ imagingcomprising a supporting structure, means carrying a detector on saidsupporting structure for movement relative thereto in a single plane,means on said supporting structure for imparting linear movement of aconstant velocity to the detector in the single plane, said meansincluding a motor having a rotatable shaft, a drive arm affixed to saidshaft, said drive arm having a cam follower at a position spaced fromits attachment to said shaft, a cam affixed to said detector, said camfollower engaging said cam, the cam having a shape to cause the detectorto be linearly reciprocated at a constant velocity across and backthrough the said single plane by rotation of said motor shaft in asingle direction at a constant speed, means for continuously moving saiddetector at a considerably lesser but constant velocity in a directionat substantially right angles to the linearly reciprocating movementobtained by the cooperating cam and cam follower, whereby the detectoris moved in a zig-zag manner throughout the single plane to therebycompletely and uniformly scan a generally rectangular area.

2. A drive mechanism for a rectilinear scanner for organ imagingcomprising a supporting structure, means carrying a detector on saidsupporting structure for movement of the detector relative to thesupporting structure in a single scan plane, drive means arranged andconstructed to cause the detector to continuously move at a constantslow velocity from top to bottom of the scan plane and further to causethe detector to reciprocate at a constant relatively fast velocity fromside-to-side of the scan plane to thereby impart a zigzag movement ofthe detector in the single plane whereby the detector may scan the wholeof a patients organ.

3. A device as set forth in claim 2 in which that part of the said drivemeans causing the detector to continuously move at a constant slowvelocity from top to bottom of the scan plane comprises a motordrivenscrew.

4. A device as set forth in claim 3 in which that part of the said drivemeans causing the detector to reciprocate at a constant relatively fastvelocity from side-to-side of the scan plane comprises a motor drivenrotating arm having a cam follower on its outer end and a cooperativecam associated with said detector.

5. A drive mechanism for a rectilinear scanner for organ imagingcomprising a supporting structure, a frame, means carrying said frame onsaid supporting structure for movement relative thereto, said meanscarrying said frame including spaced apart parallel guide rods on thesupporting structure and sleeve bearing members on said frame forslidably receiving said guide rods, means on said supporting structurefor imparting movement to the frame in the direction of said guide rods,said means on the supporting structure comprising a motor driven screwto impart movement of the frame at a constant slow velocity in onedirection, a table, a detector for scanning organs mounted on saidtable, means carrying said table on said frame for movement relativethereto, means on said frame for imparting movement to the table, saidmeans carrying said table including spaced apart parallel guide rods onthe frame disposed at right'angles to the guide rods carrying the frameon the supporting structure whereby movement of the table is in thedirection of the guide rods carrying the table, said means on said framefor imparting movement to the table including a motor having} rotatableshaft, a drive arm affixed to said shaft, said drive arm having a camfollower at a position spaced from its attachment to said shaft, a camaffixed to said table, said cam follower engaging said cam, the camextending generally diagonally of the table and arranged in generalparallelism with the axes of the guide rods, whereby the rota tion ofthe motor shaft in one direction at a constant speed will produce areciprocating action of the table at a constant speed linear velocityand considerably faster than the simultaneous movement of the frame bythe motor driven screw whereby the resultant movement of the detector isa zig-zag path over the entire organ being scanned.

1. A drive mechanism for a rectilinear scanner for organ imagingcomprising a supporting structure, means carrying a detector on saidsupporting structure for movement relative thereto in a single plane,means on said supporting structure for imparting linear movement of aconstant velocity to the detector in the single plane, said meansincluding a motor having a rotatable shaft, a drive arm affixed to saidshaft, said drive arm having a cam follower at a position spaced fromits attachment to said shaft, a cam affixed to said detector, said camfollower engaging said cam, the cam having a shape to cause the detectorto be linearly reciprocated at a constant velocity across and backthrough the said single plane by rotation of said motor shaft in asingle direction at a constant speed, means for continuously moving saiddetector at a considerably lesser but constant velocity in a directionat substantially right angles to the linearly reciprocating movementobtained by the cooperating cam and cam follower, whereby the detectoris moved in a zig-zag manner throughout the single plane to therebycompletely and uniformly scan a generally rectAngular area.
 2. A drivemechanism for a rectilinear scanner for organ imaging comprising asupporting structure, means carrying a detector on said supportingstructure for movement of the detector relative to the supportingstructure in a single scan plane, drive means arranged and constructedto cause the detector to continuously move at a constant slow velocityfrom top to bottom of the scan plane and further to cause the detectorto reciprocate at a constant relatively fast velocity from side-to-sideof the scan plane to thereby impart a zig-zag movement of the detectorin the single plane whereby the detector may scan the whole of apatient''s organ.
 3. A device as set forth in claim 2 in which that partof the said drive means causing the detector to continuously move at aconstant slow velocity from top to bottom of the scan plane comprises amotor driven screw.
 4. A device as set forth in claim 3 in which thatpart of the said drive means causing the detector to reciprocate at aconstant relatively fast velocity from side-to-side of the scan planecomprises a motor driven rotating arm having a cam follower on its outerend and a cooperative cam associated with said detector.
 5. A drivemechanism for a rectilinear scanner for organ imaging comprising asupporting structure, a frame, means carrying said frame on saidsupporting structure for movement relative thereto, said means carryingsaid frame including spaced apart parallel guide rods on the supportingstructure and sleeve bearing members on said frame for slidablyreceiving said guide rods, means on said supporting structure forimparting movement to the frame in the direction of said guide rods,said means on the supporting structure comprising a motor driven screwto impart movement of the frame at a constant slow velocity in onedirection, a table, a detector for scanning organs mounted on saidtable, means carrying said table on said frame for movement relativethereto, means on said frame for imparting movement to the table, saidmeans carrying said table including spaced apart parallel guide rods onthe frame disposed at right angles to the guide rods carrying the frameon the supporting structure whereby movement of the table is in thedirection of the guide rods carrying the table, said means on said framefor imparting movement to the table including a motor having a rotatableshaft, a drive arm affixed to said shaft, said drive arm having a camfollower at a position spaced from its attachment to said shaft, a camaffixed to said table, said cam follower engaging said cam, the camextending generally diagonally of the table and arranged in generalparallelism with the axes of the guide rods, whereby the rotation of themotor shaft in one direction at a constant speed will produce areciprocating action of the table at a constant speed linear velocityand considerably faster than the simultaneous movement of the frame bythe motor driven screw whereby the resultant movement of the detector isa zig-zag path over the entire organ being scanned.